def get_datemath()

in curator/helpers/date_ops.py [0:0]

• 25 lines of code
• 6 McCabe index (conditional complexity)

def get_datemath(client, datemath, random_element=None):
    """
    :param client: A client connection object
    :param datemath: An elasticsearch datemath string
    :param random_element: This allows external randomization of the name and is only
        useful for tests so that you can guarantee the output because you provided the
        random portion.

    :type client: :py:class:`~.elasticsearch.Elasticsearch`
    :type datemath: :py:class:`~.datemath.datemath`
    :type random_element: str

    :returns: the parsed index name from ``datemath``
    :rtype: str
    """
    logger = logging.getLogger(__name__)
    if random_element is None:
        random_prefix = 'curator_get_datemath_function_' + ''.join(
            random.choice(string.ascii_lowercase) for _ in range(32)
        )
    else:
        random_prefix = 'curator_get_datemath_function_' + random_element
    datemath_dummy = f'<{random_prefix}-{datemath}>'
    # We both want and expect a 404 here (NotFoundError), since we have
    # created a 32 character random string to definitely be an unknown
    # index name.
    logger.debug('Random datemath string for extraction: %s', datemath_dummy)
    faux_index = ''
    try:
        client.indices.get(index=datemath_dummy)
    except NotFoundError as err:
        # This is the magic.  Elasticsearch still gave us the formatted
        # index name in the error results.
        faux_index = err.body['error']['index']
    logger.debug('Response index name for extraction: %s', faux_index)
    # Now we strip the random index prefix back out again
    # pylint: disable=consider-using-f-string
    pattern = r'^{0}-(.*)$'.format(random_prefix)
    regex = re.compile(pattern)
    try:
        # And return only the now-parsed date string
        return regex.match(faux_index).group(1)
    except AttributeError as exc:
        raise ConfigurationError(
            f'The rendered index "{faux_index}" does not contain a valid date pattern '
            f'or has invalid index name characters.'
        ) from exc